1 files changed, 117 insertions, 0 deletions
diff --git a/lib/gitlab/import_export/reader.rb b/lib/gitlab/import_export/reader.rb
new file mode 100644
index 00000000000..19defd8f03a
--- /dev/null
+++ b/lib/gitlab/import_export/reader.rb
@@ -0,0 +1,117 @@
+module Gitlab
+  module ImportExport
+    class Reader
+
+      attr_reader :tree
+
+      def initialize(shared:)
+        @shared = shared
+        config_hash = YAML.load_file(Gitlab::ImportExport.config_file).deep_symbolize_keys
+        @tree = config_hash[:project_tree]
+        @attributes_finder = Gitlab::ImportExport::AttributesFinder.new(included_attributes: config_hash[:included_attributes],
+                                                                        excluded_attributes: config_hash[:excluded_attributes],
+                                                                        methods: config_hash[:methods])
+      end
+
+      # Outputs a hash in the format described here: http://api.rubyonrails.org/classes/ActiveModel/Serializers/JSON.html
+      # for outputting a project in JSON format, including its relations and sub relations.
+      def project_tree
+        @attributes_finder.find_included(:project).merge(include: build_hash(@tree))
+      rescue => e
+        @shared.error(e)
+        false
+      end
+
+      private
+
+      # Builds a hash in the format described here: http://api.rubyonrails.org/classes/ActiveModel/Serializers/JSON.html
+      #
+      # +model_list+ - List of models as a relation tree to be included in the generated JSON, from the _import_export.yml_ file
+      def build_hash(model_list)
+        model_list.map do |model_objects|
+          if model_objects.is_a?(Hash)
+            build_json_config_hash(model_objects)
+          else
+            @attributes_finder.find(model_objects)
+          end
+        end
+      end
+
+      # Called when the model is actually a hash containing other relations (more models)
+      # Returns the config in the right format for calling +to_json+
+      # +model_object_hash+ - A model relationship such as:
+      #   {:merge_requests=>[:merge_request_diff, :notes]}
+      def build_json_config_hash(model_object_hash)
+        @json_config_hash = {}
+
+        model_object_hash.values.flatten.each do |model_object|
+          current_key = model_object_hash.keys.first
+
+          @attributes_finder.parse(current_key) { |hash| @json_config_hash[current_key] ||= hash }
+
+          handle_model_object(current_key, model_object)
+          process_sub_model(current_key, model_object) if model_object.is_a?(Hash)
+        end
+        @json_config_hash
+      end
+
+
+      # If the model is a hash, process the sub_models, which could also be hashes
+      # If there is a list, add to an existing array, otherwise use hash syntax
+      # +current_key+ main model that will be a key in the hash
+      # +model_object+ model or list of models to include in the hash
+      def process_sub_model(current_key, model_object)
+        sub_model_json = build_json_config_hash(model_object).dup
+        @json_config_hash.slice!(current_key)
+
+        if @json_config_hash[current_key] && @json_config_hash[current_key][:include]
+          @json_config_hash[current_key][:include] << sub_model_json
+        else
+          @json_config_hash[current_key] = { include: sub_model_json }
+        end
+      end
+
+      # Creates or adds to an existing hash an individual model or list
+      # +current_key+ main model that will be a key in the hash
+      # +model_object+ model or list of models to include in the hash
+      def handle_model_object(current_key, model_object)
+        if @json_config_hash[current_key]
+          add_model_value(current_key, model_object)
+        else
+          create_model_value(current_key, model_object)
+        end
+      end
+
+      # Constructs a new hash that will hold the configuration for that particular object
+      # It may include exceptions or other attribute detail configuration, parsed by +@attributes_finder+
+      # +current_key+ main model that will be a key in the hash
+      # +value+ existing model to be included in the hash
+      def create_model_value(current_key, value)
+        parsed_hash = { include: value }
+
+        @attributes_finder.parse(value) do |hash|
+          parsed_hash = { include: hash_or_merge(value, hash) }
+        end
+        @json_config_hash[current_key] = parsed_hash
+      end
+
+      # Adds new model configuration to an existing hash with key +current_key+
+      # It may include exceptions or other attribute detail configuration, parsed by +@attributes_finder+
+      # +current_key+ main model that will be a key in the hash
+      # +value+ existing model to be included in the hash
+      def add_model_value(current_key, value)
+        @attributes_finder.parse(value) { |hash| value = { value => hash } }
+        old_values = @json_config_hash[current_key][:include]
+        @json_config_hash[current_key][:include] = ([old_values] + [value]).compact.flatten
+      end
+
+      # Construct a new hash or merge with an existing one a model configuration
+      # This is to fulfil +to_json+ requirements.
+      # +value+ existing model to be included in the hash
+      # +hash+ hash containing configuration generated mainly from +@attributes_finder+
+      def hash_or_merge(value, hash)
+        value.is_a?(Hash) ? value.merge(hash) : { value => hash }
+      end
+    end
+  end
+end